The suitability of the 91–1,094 keV γγ-cascade in 172Lu(172Yb) for perturbed angular correlation studies has been demonstrated several decades ago. In comparison with widely used probe nuclei like 111In or 181Hf its quadrupole moment and anisotropy coefficient are quite large and the life time of the intermediate state is sufficiently long. However, the effective anisotropy observed in actual experiments is generally much lower than the literature value. If this isotope is to be used for any quantitative analysis, especially in solid state investigations, it is very important to understand the origin of this discrepancy since the ratio of these values is directly related to the fraction of probe atoms in any given lattice environment. To this end, the influence of Compton events from competing cascades in the 91 keV start energy window of the 91–1,094 keV γγ-cascade was studied in a numerical simulation. It is shown that this Compton background is the main reason for the strong reduction of the observable anisotropy. A relation between the width of the 91 keV energy window and the effective anisotropy is established.